Did something or someone ever prevent you from going out in the rain (as a child, to play), perhaps your parents or siblings? Did this cause anger, fear, sadness?
Did you yourself put you into the belief that it's dangerous to go outside and swing your hips when it's raining because you might catch a cold?
Arthritis is commonly known to be an autoimmune disorder, meaning your immune system starts attacking parts of your body it shouldn't. So it could also be connected to you shifting your anger or resentment towards yourself, instead of telling anyone who told you you couldn't to x,y or z because of stupid nonsense reasons, to shut their mouth and leave you alone. (internalizing immune response instead of externalizing your defense mechanisms. defense is to the outside, it's not you who should be attacking yourself because you perhaps weren't able to defend yourself against attacks against your freedom of movement that perhaps came from outside, from others)
>A psychosomatic disorder is any physical condition that stress can help cause or make worse. Stress impacts our bodies in many ways and can affect several physical conditions, from heart disease to eczema. Stress management can go a long way to help manage psychosomatic disorders.
Your body is acting the way it is because it is giving you a signal, sending you a message. Not because you contracted some kind of "sickness" or "illness".
What prevents you from moving? Why does moving hurt?
There are tons of medical resources to do with fixing any health issue and tons of methods but above all you should recognize that there is a reason your body is sending you this message.